Investigation of void nucleation and propagation during electromigration of flip-chip solder joints using x-ray microscopy

Abstract

X-ray microscopy was employed to investigate void nucleation and propagation during electromigration in solder joints. The shape of the voids at various stages can be clearly observed. The voids became irregular when they propagated to deplete the contact opening. Growth velocity at the early stage was found to be 1.3 mu m/h under 6.5x10(3) A/cm(2) at 150 degrees C, and it decreased to 0.3 mu m/h at later stages. Formation of intermetallic compound (IMC) and compositional changes at the interface of solder/IMC on the chip side were attributed to the retarded growth rate at later stages. (c) 2006 American Institute of Physics.